Oscillator controlled measuring and controlling apparatus



Oct. 21, 1952 w. H. WANNAMAKER, JR 2,615,151

OSCILLATOR CONTROLLED MEASURING AND CONTROLLING APPARATUS Original FiledJune 22, 1944 2 SHEETS-SHEET 1 FIG. I C

INVENTOR. WILLIAM H.WANNAMAKER JR ATTORNEY.

1952 w. H. WANNAMAKER, JR 1 OSCILLATOR CONTROLLED MEASU RING ANDCONTROLLING APPARATUS Original Filed June 22, 1944 2 SHEETS-SfiET 2 L31?W i z: IBIHII i 1 r 1 [\Ullllll I IN V EN 59 WILLIAM H.WANNAMA JR.

ATTORNEY.

Patented Oct. 21, 1952 OSCILLATOR CONTROLLED MEASURING AND CONTROLLINGAPPARATUS William H. Wannamaker, Jr., Flourtown, Pa., as-

signor to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn.,a corporation of Delaware Original application June 22, 1944, Serial No.541,576, now Patent No. 2,514,918, dated July 11, 1950. Divided and thisapplication May 14, 1949, Serial No. 93,213 Y The general object of thepresent invention is to provide a novelcontrol motor drive combinationincluding an alternating current motor, and motor energizing meansoperative to rotate the motor continuously in one direction during eachperiod in which the value of a control quantity or condition is within acertain range, and to maintain the motor stationary during periods inwhich the value of said quantity orcondition is not within said range.

More specifically stated, the object 'of the present invention is toprovidea motor drive combination in which the energizing winding of analternating current motor of the shaded pole type is included in acircuitnetwork comprising two motor drive electronic valves, andprovisions responsive to variations in the value of a controllingquantity or condition for causing one of said valves to oscillate whenthe value of said quantity or condition is not within a predeterminedrange, and with said valves so arranged that when said one valve is notoscillating, the two valves supply energizing current to said windingduring alternate halves of each cycle of the alternation of thealternating current supplied tothe network to energize the latter.

My novel motor drive combination is characterized by its mechanicalsimplicity, small current requirement, small frictional losses andpositive operation.

This application is a division of my prior application Serial No.541,576, filed June 22, '1944, now

Patent No. 2,514,918,"July 11, 1950, which discloses and claims novelsubject matter disclosed but not claimed herein.

Thefvarious features of novelty which characterize my invention arepointed out with 'particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, its advantages and specific objects attained with itsuse,reference should be had to the accompanying,

drawings and descriptive matter in which I have illustrated anddescribed a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is a diagrammatic representation ofone' embodiment of theinvention.

Fig. 2 is an elevation'with parts broken away of a control'instrumentincluding the apparatus I,

shown in Fig. 1.

2 Claims. (Cl. 318-223) Fig. 3 is an inverted plan view of the controlvane portionof the apparatus shown in Fig. 2.

In Fig. 1, I have diagrammatically illustrated an embodiment of mypresent invention energized by alternating currentsupplied by conductorsl and 2, and in which a diodetetrode tube A is employed-to actuate amotor B in accordance with variations in the temperature in a furnace Cto which a thermocouple D is responsive. The motor B is arranged torotate only during periods in which the furnace temperature exceeds apredetermined value. Adevice b rotated by the shaft b of the motor B,may serve one or another of various purposes.- For example, it mayintegrate the time intervals during which the furnace temperatureexceeds a predetermined value in the general manner illustrated in Fig.2. Alternatively, the device b may serve as 'a' visual or aural in- Idicator of the furnace temperature, to which the thermocouple D isresponsive, or of the need for adjustment of the furnace heat supply bymanual adjustment of a controller E regulating the current to a furnaceheating resistor F.

As diagrammatically shown in Fig. l, the thermocouple D is connected tothe terminals of a galvanometer G including a deflecting arm G carryinga control element H at its free end, and also carrying a pointer G:cooperating with a scale G3 to indicate the thermocouple temperature. Inthe arrangement shown in Fig. 1 the controlling element H is a sheetmetal vane which operates as an induction shield to regulate the mutualinductance of juxtaposed inductance coils I and i as is hereinafter morefully explained.

As shown in Fig. 1, the tube A is of the type and form known as arectifier-beam power amplifier tube, type ll'lN'IGT. The tetrode valve ain the tube A comprises a cathode 3 and associated beam plates 30:, acontrol grid 4, a screen grid 5, an anode or plate 6, and a filament forheating both the cathode 3 of the valve (1 and the cathode 8 of thediode valve a. The diode plate 9, one terminal of the filament I andthecathode 3 are all connected to an energizing conductor [0 which isabranch of the supply conductor I, and is connected to ground through acondenser H; The second terminal of the filament 1 is connected to thesupply conductor 2 by e. conductor I2. The cathode 8 of the diode isconnected by a conductor l3 to one terminal 14 of a condenser [5. Thetetrode plate 6 is connected to the condenser terminal 14 through aninductance [6. The second terminal of the condenser I5 is connected by aconductor H to one terminal of the winding 18 which forms the energizingelement of the motor B. The second terminal of the winding 18 isconnected by a" conductor 19 to the supply conductor 2 .1

The value of condenser 15 is so chosen in relation to the inductance ofthe energizing winding I8 that the condenser I5 and energizing windingI8 form a series resonant circuit. With this value for the condenser I5the voltage drop across the energizing winding I8 is of approximatelythe same magnitude as the voltage of the supply conductors I and 2, asis also the voltage drop across the condenser I5 and also across thetube A. Such choice of the value of condenser I5, therefore, isadvantageous in that it permits full line voltage to be impressed on thewind ing I8.

The tetrode plate 5 is connected by a conductor and a condenser 2| toone terminal of the inductance or control coil I. The second terminal ofthe coil I is connected to a ground connection 22 to which is alsoconnected one terminal of the second inductance or control coil 1'. Thesecond terminal of the last mentioned coil is connected by a condenser23 and conductor 24 to the tetrode control grid 4, and the latter isconnected to the cathode 3 by a resistance 24'. The terminal I4 of thecondenser I5 is connected through a conductor 25 to the screen grid 5and to a condenser 26 which connects the conductor 25 to the conductorI0 and thereby to the supply conductor I. As shown, a resistance 21 isconnected in shunt to the inductance coil IS; the outer terminals ofcoils I and i are connected by a resistance 28; and a condenser 29connects conductor 25 to ground.

The motor B is a shaded pole, alternating current motor having its mainpoles 3I energized by current flow through the energizing winding I8 andhaving each of its shading poles 32 surrounded by a short circuitedwinding 33. The energizing winding I8 is connected between the condenserterminal I! and the supply conductor 2. In the contemplated operation ofthe apparatus shown in Fig. l, the motor B runs continuously in onedirection during periods in which the mutual inductance of the controlcoils I and z is not great enough to cause the alve a of the tube A tooscillate, and is stationary during periods in which valve a oscillates.

In the form of the invention shown in Fig. l, the actuating coil I8 ofthe motor B constitutes a control circuit load which is connectedbetween the supply conductors I and 2 in series with the condenser I 5and with each of the two electronic valves which are in parallel withone another. Since the plate 6 of the multi-grid valve a and the cathode8 of the diode valve a are connected to the same side of the condenserI5, the diode plate current flows from the cathode 8 to the condenserterminal I4 during half cycle intervals which alternate with half cycleintervals during which the grid valve plate current flows from thecondenser terminal I4 to the plate 5. By reason of the potential of thecondenser I5, built up by the conduction of the grid or power tube valvea during its half cycle of line power operation, the conduction of therectifier or diode valve is controllable. Thus the load element or motorwinding I8 receives a full wave current which is controlled bycontrolling the conduction of the multi-grid valve section of thesystem, although the latter operates only during a portion of the fullWave current cycle.

With the arrangement shown in Fig. 1, it is thus possible to control thefull wave current fiow through the coil I8 by regulating the conductionof the grid valve section of the system. That regulation may be effectedin various ways, As shown diagrammatically-in Fig. l, the conduction ofthe grid valve section is regulated by varying the position of the ane Hrelative to the inductance coils I and i, and thereby so varying themutual inductance of the coils that the grid valve a will not oscillatewhen the thermocouple temperature D is at, or above, the desired value,and will oscillate when the thermocouple temperature is lower.

When the thermocouple temperature is so low as to result in grid valveoscillation, the current flow through each valve is small and theresultant current flow through the motor winding I8 does not operativelyenergize the motor B. When the temperature of the thermocouple D is ator above the desired value, the galvanometer G moves the vane H into aposition in which it so reduces the mutual inductance of the coils I andi that the valve a ceases to oscillate. When this occurs, the currentflow through the grid valve section of the system becomes relativelyhigh as does the current flow through the diode valve of the system. Inconsequence, the current now through the motor winding I8 is thensufficient to maintain the rotation of the motor B and device I).

The inductance of the coil I8 is advantageously so related to thecapacitance of the condenser I5 as to tune the circuit including themand thus further raise the voltage of the condenser I5. The full wavecurrent flow through the coil It provides about twice as much energy forthe actuation of the motor 13 as would be available if the diode valve adid not supply current during the half cycle period in which the currentflow through the multi-grid valve is interrupted.

The control system shown in Fig. 1 is thus characterized by its inherentcapacity for supplying suflicient power for the positive operation ofthe motor B. While other means for regu-.

lating the conditionot the multi-grid valve section of the system may beused, the means shown in Fig. l are especially advantageous because ofthe inherent simplicity, reliability and sensitivity of operation of theinductance coils I and i and inductance shield vane H when they aresuitably formed and disposed. A practically desirable arrangement ofsaid coils and vane is illustrated in Figs. 2 and 3.

In Figs. 2 and 3, I have illustrated the use of the invention showndiagrammatically in Fig. 1 in a measuring instrument GA to provide anintegration of the time intervals during which.

the value of a. quantity measured by the instrument exceeds apredetermined value. The instrument GA includes a vane HA which differsin form but not in principle of operation from the vane H. The vane HAis an arc shaped body of sheet metal of good conductivity, such asaluminum, copper or brass attached to a rotatable support 40. The latteris mounted on a horizontal pivot 4I carriedby the mechanism casing 42and is suitably counterweighted to free the vane from gravitationalbias. The inductance coils I and i are fiat spirals each mounted on anindividual support 43. In the practically desirable form illustrated,the two supports 43 are counterparts. The two coil supports 43 areadvantageously connected to form a single mechanical unit by a metalliceyelet or hub part 45 which extends through a portion of each supportdisplaced from its boss 44. Figs. 2 and 3, the unit including the coilsI and i and their supports 43 are detachably secured by a clamping screw48 to the end of a post portion 49 of the casing 42.

As shown in The inductance coil construction just describedismechanically simple and relatively inexpensive'and is especiallydesirable because it permits-the coils I and i to be accurately spaceddesirably close toone another, so that a very small angular movement ofthe sheet metal vane HA in the inner kerf-like space between the twocoils may produce a relatively large change-in the mutual inductance ofthe coils, while permitting each of the latter to comprise but a fewturns or convolutions. The construction and arrangement of the supports43 and the coils I and i are fully disclosed in my above mentionedapplication, and are also described and are claimed in my priorapplication Serial No. 541,575, filed June 22, 1944, and now Patent No.2,531,313 of November 21, 1950.

In the instrument shown in Fig. 2, the vane HA is oscillated about thepivot 4| through a pin and slot connection between the vane support4|Jand a rocker or lever element mounted on a pivot pin 50 andcomprising two lever arms and 52. The arm 5| carries a pin 53 receivedin'an elongated slot 54 formed in the vane support 40' and: extending ina general radial direction away from the pivot 4|. The second arm 52 ofthe rocker element is pivotally connected to one end of an actuatinglink 55 which has its second end connected through a lever and linkarrangement of known type to an arm 51 oscillating in accordance withchanges in the value of the controlling condition. As shown in Fig. 2,the arm 51 is connected to the free end of a Bourdon tube 58 which hasits other end anchored to the instrument casing and connected to one endof a capillary tube 59 through which a variable controlling fluidpressure is transmitted to the Bourdon tube 58. In consequence, the arm51 oscillates about the axis of the Bourdon tube in the clockwise orcounter-clockwise direction, as the pressure transmitted by thecapillary 59 respectively decreases or increases.

The known type of link and lever arrangement through which the link 55is adjusted longitudinally in accordance with angular adjustments of thearm 51, comprises a lever element 60 journaled on a pivot 6| carried bythe instrument casing and having one arm connected by a link 62 to thearm 51. A second arm of the lever 60 is connected by a link 53 to oneend of a floating lever 64. The other end of the floating lever 54 ispivotally connected by a pivot 65 to a control point adjusting element56. The latter is pivotally mounted on a pivot pin 81 carried by theinstrument casing. The element 85 may be angularly adjusted about thepivot 51 by means including a spur gear 68 in mesh with a spur gearportion 66 of the member 56. The spur gear 68 may be rotated by gearingincluding an adjusting shaft 59 journaled on the instrument casing, andshown as formed with a kerf in one end for screwdriver adjustment. Theend of the link 55 remote from the rocker arm 52 is pivotally connectedto the floating lever 84 intermediate the ends of the latter. The member55 includes an index arm 10 which indicates on the rotating instrumentchart 1| the control point or value which the instrument is intended tomaintain approximately constant. The actual value of that controlcondition is indicated and recorded on the chart 1| by a pen 12 carriedat the free end of a pen arm 13 mechanically connected to the lever 60so as to turn about the pivot 6| in accordance with changes in-the valueof the pressure transmitted by the capillary 59. a

The Bourdon spiral 58 may be connected through the capillary tube 59 toany controlling fluid pressure source. Thus, for example, that sourcemay be a fluid pressure thermometer bulb DA as shown in Fig. 2, and insuch case the instrument GA may be employed in the control system showndiagrammatically in Fig. l to give the vane HA oscillatory movementsrelative to the coils land 1' on changes in the temperature of the bulbDA which are similar to the relative movements of the vane H and coilsproduced in the particular arrangement shown in Fig. 1 by the responseof the ,galvanometer G to variations in the voltage of the thermocoupleD. Regardless of the origin of the controlling pressure, its decrease orincrease efiects a turning movement of the vane HA clockwise orcounterclockwise respectively about its pivot 4|.

The exact angular position of the vane HA at which the valve will ceaseto oscillate depends on various control system constants. Ordinarily,however, it will be a position in which the vane edge 15 extends betweenthe bosses 44 of the two coil supports 43 approximately as shown in Fig.2. Control apparatus comprising an electronic valve adapted to beadjusted into or out of an oscillating condition by changes in therelative positions of an inductance shield vane HA and inductance coilsI and i of the type and form shown in Figs. 2 and 3, may be soconstructed and arranged that the valve a will be caused to oscillate orto cease from oscillation by a movement of the portion of the vane edge15 adjacent the axes of the coils I and i, of the order of one or twothousandths of an inch.

With the pin and slot connection between the rocker arm 5| and the vaneHA shown in Fig. 2, the ratio of the angular movement of the vane androcker arm is relatively very large when the pin 53 is close to thepivot 4| and to the plane including the axes of the pivots 4| and 50,and said ratio diminishes as the pin moves away from said plane.Advantage of the pin and slot connection characteristic just mentioned,may be taken to make the instrument especially sensitive in the range ofvane movement in which such sensitivity is especially important. Usuallymaximum sensitivity is especially desirable when the vane is in and nearthe position at which oscillation begins and stops. No claim is madeherein on said pin and slot arrangement, as that arrangement wasinvented by Edwin C. Burdick, and is claimed in his application Ser. No.541,510, filed June 22, 1944, and now Patent No. 2,481,820 of September13, 1949.

For the purposes of the present invention, the motor B included in theinstrument GA has its shaft b connected through suitable speed reducinggearing B to the shaft 13* of a counting train 13 to thereby provide anintegration of the time intervals during which the temperature of thepressure bulb DA exceeds the desired value. In operation with a smallsteady load such as the integrator B the motor B of Fig. 2 operates as asynchronous motor having a speed which is in predetermined constantproportion to the frequency of the alternating current supplied by thesupply condensers and 2.

While, in accordance with the provisions of the statutes, I haveillustrated and described the best form of embodiment of my inventionnow known to me, it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus'disclosed withoutdeparting from the spirit of my invention as set forth in the appendedclaims, and that in some cases certain features of my invention maybeused to advantage without a corresponding use of other features.

Having now describedmyinvention, what I claim as new and desire tosecure by Letters Patent is:

1. A motor drive mechanism comprising in combination,'an alternatingcurrent motor having main poles and shading poles, a short circuitedwinding energizing said shading poles, a circuit network having a pairof terminals adapted to be connected across a source of alternatingcurrent, and including a Winding energizing said main poles, acondenser, and two electronic valves connected between said terminals inparallel with one another and in series with said winding and condenser,one of said valves being a diode and the second valve having a controlgrid and having its cathode connected to the anode of said diode so thatcurrent may flow through each valve during half cycles alternating withthose during which'current flows through the other valve, and meansresponsive to a control H. WANNAMAKER, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,993,527 Mears et a1. Mar. 5,1935 2,112,683 Wooley Mar. 29, 1938 2,351,760 Beers June 20, 19442,411,247 Cohen Nov. 19, 1946 2,473,494 Wannamaker June 14', 19492,514,918 Wannamaker July 11, 1950

